class LazyWeak<T> { private weak var _value: T? = nil private func undefined() -> T { fatalError() } var value: T { get { return _value ?? undefined() } set { _value = value } } } class VM { var vc = LazyWeak<VC>() } こういうイメッジclass LazyWeak<T> { private weak var _value: T? = nil private func undefined() -> T { fatalError() } var value: T { get { return _value ?? undefined() } set { _value = value } } } class VM { var vc = LazyWeak<VC>() } こういうイメッジ